Most Frequently Used Coordinate System
In the ArcCatalog, drag and drop your most frequently used coordinate systems into the top level of the Coordinate Systems folder to put a copy of them into that location for quick access to them on dialog boxes.
o In ArcCatalog, choose Customize ► ArcCatalog Options… from the main menu bar. In the General tab and check the box next to Coordinate Systems.
o Expand the Coordinate Systems folder to where your desired coordinate systems are and then drag them up to the main Coordinate Systems folder.